Various methods for control of insertion devices have been devised. While many of these methods can work quite well, there are no easy solutions for dealing with jams or other problems created because of the "inflexibility" associated with the known synchronous mechanical insertion devices which rely only on the timed operation of the various corresponding steps in order to assure that the collation or material to be inserted is appropriately placed to be guided and inserted into an envelope waiting to receive the insert. It has become apparent that these devices are unforgiving of the various conditions that can occur during the operation of handling paper and any problems that do occur, such as for example, an out of tolerance skew of an envelope, can require a significant investment in time in order to clear the apparatus and begin the process at an appropriate restart point. U.S. Pat. No. 3,709,482 to Nelson, et al describes a high speed document feeder using synchronous operation.
U.S. Pat. No. 3,825,251 discloses a system for controlling the feed of documents into and along a document path. The device can be made to operate synchronously if the longest document length is used to determine the maximum throughput or asynchronously in that the document by its own length may be used to determine the throughput rate. The lengths in the asynchronous mode are used to adjust the speeds of various rollers in the document path to determine the degree of inter-document spacing. This reference does not deal with the problems of attempting to assure that one event such as the placement of an envelope matches the arrival of an insert. U.S. Pat. No. 3,773,316 to Stemmle teaches a drive mechanism which is used to provide reverse buckle feeding of an individual sheet from a stack by imparting an asynchronous multi-directional motion.
U.S. Pat. No. 5,003,485 describes an asynchronous communication protocol for a collating and insertion device. U.S. Pat. No. 5,012,073 describes a card and mailer data inserter system which includes an operator means for manual override and a means for re-initiating automatic operation.